1. Field of the Invention
The present invention relates to an image forming apparatus, a controlling method for the same, and a storage medium.
2. Description of the Related Art
The publication of printed matter in the commercial printing industry includes various steps such as sending of a manuscript, design or layout, overall layout (presentation by a printer output), proofreading (layout correction, color correction), proof sheet printing, block copy formation, printing, post-processing, and shipping. The commercial printing industry executes the aforementioned steps using a large-scale printing apparatus or the like, such as an offset photoengraving printer or the like. Among the aforementioned steps, the block copy formation is important. However, once the block copy has been formed, its correction is not easy, and thus, it is fairly disadvantageous in terms of costs. Thus, careful proofreading (a check of the layout and a color confirming operation) is indispensable, and it also takes a certain amount of time to make printed matter.
On the other hand, in recent years, the realization of a high speed and high quality picture by an electrophotographic-type image forming apparatus or an ink jet-type image forming apparatus has been progressing. Hence, in opposition to such a commercial printing industry, a market called a Print On Demand (hereinbelow, abbreviated as “POD”) is growing. In the POD market, it is intended that a job of a relatively smaller lot than a job which is handled by a printing apparatus can be handled in a tight delivery date without using a large-scaled apparatus.
In the POD market, digital print using electronic data is realized by the use of digital image forming apparatuses such as digital copiers or digital multi-function peripherals. By doing so, the POD market is trying to come close to a printing industry level to some extent utilizing a computer. Among them, there has been an increase in demand of variable printing (Variable Data Printing) for printing data in response to each customer need. A variable printing job (VDP job) prints customer data corresponding to one VDP job for each record unit. Thus, one VDP job includes a large amount of records (e.g., tens of thousands of records).
Each record included in a VDP job includes a variable object serving as variable data and a reusable object that is shared among a plurality of pages. An image forming apparatus acquires an object(s) included in a VDP job and performs rendering processing to thereby generate a bitmap image. When the rendering processed object is a reusable object, the image forming apparatus stores a rendering processed reusable object in a predetermined cache region. Then, the image forming apparatus arranges the rendering processed variable object and reusable object on each page included in a VDP job for printout.
Here, when a reusable object is stored in a cache region, the image forming apparatus reads out the reusable object from the cache region, and arranges the readout reusable object on a page together with the variable object. On the other hand, when the reusable object is not held in the cache region, the image forming apparatus performs new rendering processing for the reusable object, and arranges the rendering processed reusable object on a page. In other words, in this case, the image forming apparatus generates the bitmap image (image data) of the reusable object as so-called “image data of a variable object”.
As a technology for inspecting printed matter in the commercial printing industry or the POD market, Japanese Patent Laid-Open No. 2006-297739 discloses a print system that acquires an image by imaging printed matter and extracts a defective page based on the comparison result between the acquired image and the image for inspection.
However, if there is no room in the cache region provided by the image forming apparatus and the image forming apparatus reprints a defective page, the following problems may occur. When the image forming apparatus reprints a defective page and a reusable object included in the defective page is not held in the cache region, the image forming apparatus must perform rendering processing for the reusable object again. When the reusable object is subject to rendering processing again, such processing takes tens of times more than the case where the rendering processed reusable object is read out from the cache region so as to be used for printing. Consequently, the efficiency of reprint processing for a defective page(s) decreases.